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This paper describes a simple performance-based approach for estimating fire-resistance of reinforced concrete columns, within a building frame, by considering the effect of the structural system and thermal expansion phenomenon. The attempt was made to develop an analytical tool for application of the new performance-based design philosophy, using evaluation of structural performance in fire, considering the entire structural system rather than individual elements. This method describes how to determine fire performance of a reinforced concrete column when it is part of a structural frame. In this approach, the entire frame is simplified into a single equivalent spring and coupled with the column. The column is then exposed to fire and, according to the column deformation and the equivalent frame spring stiffness, the test load, restraint force, is determined. Frames with different numbers of stories and height were selected for the analysis. These were modeled using a structural analysis program, the SAFIR program, and the outcomes were compared with those of the simplified approach, developed through this study, resulting in a consistent agreement. An example including the analytical process is presented for one of the reinforced concrete column tests. The results from this study show that the simple performance-based approach is a suitable and easy to use tool for fire-resistance assessment of reinforced concrete columns. This research report provides theoretical concept and formulation of the new test process. For application in practice, the model needs to be verified through a future experimental program. |
